Packet #4 Chapter 13 Sections 1 & 3 Solution Chemistry Packet #4 Chapter 13 Sections 1 & 3

Introduction Solutions are homogenous (everywhere the same) mixtures of substances that combine to form a single phase (generally liquid). Recall that a mixture is a physical blend of two or more substances. Mixtures may not be always a liquid Example Smoke in air

Solutions vs. Suspensions A suspension is a temporary heterogeneous mixture. A type of mixture in which the different parts spontaneously separate over time. Clay and water Over time, the clay eventually settles to the bottom.

Solutions vs. Suspensions Solutions stay “uniform” over time and the substances do not separate.

Parts of a Solution

Parts of a Solution There are two general parts of a solution Solvent The primary ingredient Present in large amounts Solute The other ingredients found in much smaller portions

The Water Connection Water is the most common solvent. Furthermore, any solution that contains water, as the solvent, is an aqueous solution.

Colloids

Introduction Colloids are stable heterogeneous mixtures that resemble homogenous mixtures. Colloid is derived from a Greek word meaning glue-like. Milk is a colloid that contains globules of fat and small lumps of protein casein. Mayonnaise is a colloid that contains water droplets in oil.

Separation of Mixtures

Separation of Mixtures There are multiple ways of separating mixtures.

Separation of Mixtures II Separation of Mixtures at Home Using a filter to make coffee Evaporation that occurs when cooking Leading to the burning of one’s food

Separation of Mixtures III Separating Mixtures in a Lab Centrifugation The use of a centrifuge, spinning up to 80,000 revolutions per minute and increasing the force of gravity up to ** times what is seen on earth, can separate substances found in mixtures based upon the different sizes of the molecules.

Separation of Mixtures IV Chromatography Separation is based on how quickly the components in the mixture is dissolved in a mobile phase solvent. Paper chromatography is is a useful technique for separating components of a solution.

Separation of Mixtures V Distillation Separates components based on the boiling points One component reaches its boiling point faster than the other(s). Is this how salt is obtained from the ocean?

Solubility

Definition The solubility of a substance is the maximum amount of that substance that can be dissolved in a particular solvent at a particular temperature.

Solubility II Glucose, a type of sugar, will dissolve in 100ml of H2O until a maximum amount has been added (83g) Once the maximum has been achieved, the solution is said to be in equilibrium and is saturated.

Solubility III A solution that is below the saturation point is described as undersaturated solution. A solution that is above the saturation point, where added substance precipitates at the bottom is described as a supersaturated solution. Concentrated Solution.

Dissolving Gases in Liquids

The Soda Bottle CO2 resides above the liquid before the bottle is opened and is in equilibrium with the gas in the liquid. The solution is at the point of saturation. When the bottle is opened, the CO2 is no longer in equilibrium with the CO2 in the air and escapes the bottle/liquid in an attempt to reach that equilibrium point.

The Soda Bottle II Henry’s Law At a constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas on the surface of the liquid.